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'Antioxidant' berries, anthocyanins, resveratrol and rosmarinic acid oxidize hydrogen sulfide to polysulfides and thiosulfate: A novel mechanism underlying their biological actions.
- Source :
-
Free Radical Biology & Medicine . Mar2021, Vol. 165, p67-78. 12p. - Publication Year :
- 2021
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Abstract
- Nutraceutical polyphenol catechins in green tea oxidize H 2 S to polysulfides (PS) in buffer and in cells thereby conveying their cytoprotective effects. Here we measure H 2 S oxidation in buffer and HEK293 cells by over-the-counter nutraceuticals, blueberry, bilberry and cranberry, and by polyphenols, cyanadin (Cya), quercetin (Que), rosmarinic acid (RA) and resveratrol (Res). H 2 S and PS were measured with specific fluorophores, AzMc and SSP4 respectively, and thiosulfate (TS) production was measured in buffer using silver nanoparticles (AgNPs). All compounds increased polysulfide production from H 2 S in buffer and increased polysufides in cells. Decreasing oxygen from 100% to 21% and 0% progressively decreased PS production by Que and RA in buffer and Que decreased PS production in cells incubated in 5% O 2 compared to 21% O 2. Que, RA and Res, but not Cya, increased TS production from H 2 S in 21% O 2 but not in 0% O 2. Superoxide dismutase did not affect PS production from H 2 S by Que or TS production from H 2 S by Que, RA or Res, whereas catalase inhibited TS production by all three polyphenols. Conversely, these polyphenols only slightly reduce a mixed polysulfide (K 2 S n) or thiosulfate to H 2 S in 0% O 2. Collectively, our results suggest that polyphenols are autoxidized to a semiquinone radical and that this, in turn, oxidizes H 2 S to a thiyl radical from which polysulfides and thiosulfate derived. They also suggest that this is catalyzed by a semiquinone radical and it is independent of either superoxide or hydrogen peroxide concomitantly produced during polyphenol autoxidation. The polysulfides produced in these reactions are potent antioxidants and also initiate a variety of downstream cytoprotective effector mechanisms. It is also possible that H 2 S can be regenerated from the thiosulfate produced in these reactions by other cellular reductants and reused in subsequent reactions. [Display omitted] • Health benefits of nutraceutical polyphenols (NP) are attributed to their antioxidant activity. • Autoxidation of NPs produces oxidative semiquinones. • Semiquinones oxidize hydrogen sulfide (H 2 S) to polysulfides. • Polysulfides are potent antioxidants and activate antioxidant effector mechanisms. • We propose that many health benefits of NPs are mediated by sulfur metabolism. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 08915849
- Volume :
- 165
- Database :
- Academic Search Index
- Journal :
- Free Radical Biology & Medicine
- Publication Type :
- Academic Journal
- Accession number :
- 149155035
- Full Text :
- https://doi.org/10.1016/j.freeradbiomed.2021.01.035